JP5016957B2 - Manufacturing method of mold having uneven structure, mold for optical element, and optical element - Google Patents

Description

The present invention relates to a mold having an uneven structure, a method for manufacturing a mold for optical elements, and an optical element.
In particular, an optical element molded using the optical element mold according to the present invention has a function of suppressing the amount of light reflected from the interface on the light incident / exit surface. For example, it is suitable for an imaging device such as a camera or a video camera, or a projection device such as a liquid crystal projector or an optical scanning device of an electrophotographic device.

  In general, an optical element that needs to suppress the amount of light reflected on the surface obtains desired reflection characteristics by laminating a single layer or a plurality of layers with an optical film having a different refractive index on its surface to a thickness of several tens to several hundreds of nanometers. . In order to form these optical films, vacuum film formation methods such as vapor deposition and sputtering, and wet film formation methods such as dip coating and spin coating are used. Regardless of which film forming means is used, the optical element substrate must be processed and then formed into a film, which makes it difficult to manufacture and there are restrictions in reducing the cost.

  On the other hand, it is known that the amount of reflected light at the interface can be suppressed by forming a fine shape with a pitch equal to or less than the design wavelength on the surface of the optical element without using an optical film. If the fine shape can be formed on the mold using this principle, and the optical element can be manufactured together with the molding of the substrate, the manufacturing cost can be ultimately reduced.

  Conventionally, a semiconductor process called SWS (Sub Wave-length Structure), which is a technique for forming a fine shape, has been widely used. However, this method has an advantage that a precisely designed SWS can be formed. However, there are many restrictions when forming a large area on a curved surface, and there is a problem that it is very difficult to manufacture inexpensively (simplely).

On the other hand, a method of forming by using fine particles has been proposed as one of methods for easily manufacturing SWS (see, for example, Patent Documents 1 and 2).
In Patent Document 1, when fine particles are used, SWS can be formed in a large area all together. However, since the SWS is formed by continuously and uniformly arranging the fine particles, it is difficult to control the volume ratio and aspect ratio of the base material and the atmosphere that determine the reflection characteristics, and it is difficult to obtain an ideal antireflection effect. There was a problem.

On the other hand, an anodic oxidation method is known as a method capable of forming SWS in a large area at low cost and controlling the aspect ratio arbitrarily. Fine pores are formed by applying a metal such as aluminum as an anode in an acidic electrolyte and oxidizing it. Utilizing this fact, a method for regularly arranging holes, a method for filling holes with different materials, and the like have been developed (see, for example, Patent Documents 3 and 4).
JP 2000-071290 A JP 2001-074919 A JP-A-2-254192 JP-A-10-121292

  When light enters the optical element, unnecessary reflected light is generated on the incident / exit surface of the optical element. A problem caused by the reflected light generated on the incident / exit surface of the optical element at this time will be described using a conventional laser beam printer (LBP) as an example. However, the problem to be solved by the present invention is a defect due to Fresnel reflection occurring at the interface where light enters and exits, and is not limited to the reflection of the solid surface.

FIG. 10 is a cross-sectional view (main scanning cross-sectional view) of the main part in the main scanning direction of a conventional optical scanning device used for LBP and the like.
In the figure, a divergent light beam emitted from the light source means 1 is made into a substantially parallel light beam or a convergent light beam by the collimator lens 8, and the light beam (light amount) is shaped by the aperture stop 3 to have a refractive power only in the sub-scanning direction. 4 is incident. Out of the light beam incident on the cylindrical lens 4, the light beam exits as it is in the main scanning section, converges in the sub-scanning section, and converges in the vicinity of the deflecting surface 5 a of the optical deflector 5 composed of a rotating polygon mirror (polygon mirror). It is formed almost as a line image.

  Then, the light beam reflected and deflected by the deflecting surface 5a of the optical deflector 5 is passed through an imaging optical means (fθ lens system) 6 having two fθ lenses 6a and 6b having fθ characteristics. The light is guided onto the surface 7. Then, by rotating the optical deflector 5 in the direction of arrow A, the photosensitive drum surface 7 is optically scanned in the direction of arrow B (main scanning direction) to record image information.

  In recent years, the fθ lens (optical element) constituting the imaging optical means is often formed in a free-form surface shape, and it is becoming common to produce the shape with a plastic material that is easy to manufacture.

  However, since it is difficult to apply an antireflection film to the lens surface due to technical and cost reasons, plastic lenses may omit the antireflection film, causing surface reflection on each optical surface and causing problems. was there. That is, the surface reflected light generated on the fθ lens surface from which the antireflection film is omitted may be reflected by other optical surfaces and finally reach an unintended portion of the surface to be scanned, thereby causing a ghost phenomenon.

  In particular, as shown in FIG. 10, when the optical surface (fθ lens surface) 6a1 that is relatively close to the optical deflector 5 is concave and the incident light beam has an incident angle close to vertical, of the two fθ lenses, the optical surface The surface reflected light at 6a1 returns to the optical deflector 5. Then, after re-reflecting on the deflecting surface (reflecting surface) 5a of the optical deflector 5 and passing through the imaging optical means 6, it may reach an unintended part on the photosensitive drum surface 7 to cause a ghost. there were.

  Accordingly, an object of the present invention has been made to solve the above-described problem, and an optical element capable of obtaining uniform antireflection characteristics over the entire optical surface of an optical element having a finite curvature, and its optical It aims at providing the manufacturing method of the metal mold | die for elements.

The above problem is solved by the following means according to the present invention.
That is, the mold manufacturing method of the first invention is a mold manufacturing method having a concavo-convex structure on a substrate, and the first material and the second material phase-separated from the first material on the substrate. A plurality of cylinders containing the first material obtained by the film forming step as a component, and a matrix region comprising the second material surrounding the plurality of cylinders as a component. Then, the matrix region is removed from the mixed film containing nickel in at least one of the first and second materials. And a step of producing a mold made of the first material.

  A mold manufacturing method according to a second invention is a mold manufacturing method having a concavo-convex structure on a substrate, wherein a first material and a second material phase-separated from the first material are simultaneously formed on the substrate. A step of forming a film. And a matrix region containing the first material obtained by the film forming step as a component, and a plurality of cylinders containing the second material surrounded by the matrix region as a component. The cylinder portion is removed from the mixed film containing nickel in at least one of the second material and the second material. And a step of producing a mold made of the first material.

According to a third aspect of the present invention, there is provided an optical element mold manufactured by the above-described optical element mold manufacturing method.
Furthermore, the optical element of the fourth invention is characterized by being molded using the optical element mold of the third invention.

  A mold manufacturing method according to a fifth aspect of the present invention is a mold manufacturing method having a concavo-convex structure on a substrate, wherein a first member and a second member phase-separated from the first member are simultaneously formed on the substrate. A columnar member composed of one phase is dissolved from a mixed film having a two-phase separation structure composed of the first and second columnar members obtained by the film-forming step and the first and second columnar members. And a step of producing a mold made of a columnar member composed of the other phase.

  According to a sixth aspect of the present invention, there is provided a mold manufacturing method, wherein the concavo-convex structure is a mixed film having a two-phase separation structure in which a plurality of the concavo-convex structures are arranged on the substrate and configured by the first and second columnar members. The ratio of the average diameter Dl in the major axis direction to the average diameter Ds in the minor axis direction in any one of the phases is 5 or more, and the period of the concavo-convex structure is in the range of 30 nm to 500 nm. And the depth of the concavo-convex structure is 100 nm or more.

  Further, the present invention relates to a method for manufacturing a mold, and the mold here is, for example, a mold. However, the present invention includes not only a mold made of only a metal material, but also a mold made of a material other than a metal, or made of a metal material and a material other than the metal.

ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the type | mold which has an uneven structure on a board | substrate, and the type | mold for optical elements can be provided.
In addition, according to the present invention, an optical element that can easily form a plurality of pores on the surface of an optical element using a cylindrical or conical nickel or nickel alloy mold for an optical element is provided. A method can be provided.

  Alternatively, according to the present invention, there is provided an optical element in which a plurality of protrusions can be easily formed on the surface of an optical element using a mold for optical element made of nickel or a nickel alloy having a cylindrical or conical uneven structure. A manufacturing method can be provided.

  According to the present invention, there is provided an optical element capable of obtaining uniform antireflection characteristics over the entire optical surface by providing a plurality of pores having an antireflection function on the surface of the optical element having a finite curvature. Can be provided.

  Furthermore, according to the present invention, by mounting the optical element on an optical device, it is possible to eliminate problems caused by reflected light on the surface of the optical element, and to realize high brightness and energy saving by increasing the amount of transmitted light. It is possible to provide an optical apparatus that can

Hereinafter, the present invention will be described in detail with reference to embodiments, but the present invention is not limited to the following embodiments.
[Mold manufacturing method]
The manufacturing method in the case of using an aluminum nickel mixed film is demonstrated about the manufacturing method of the metal mold | die which has a convex-concave uneven structure on the board | substrate of this invention.

When the aluminum nickel mixed film is formed in a non-equilibrium state, the following is obtained.
A plurality of cylinders mainly composed of aluminum nickel (Al ₃ Ni) and a matrix region composed of aluminum (Al) surrounding the cylinders are grown in a phase-separated state. Then, as shown in FIG. 1, a structure in which a cylindrical aluminum nickel (Al ₃ Ni) 12 portion is divided by an aluminum (Al) matrix region 13 is formed. At this time, the shape of the cylindrical aluminum nickel (Al ₃ Ni) 12 includes a cylindrical shape, a polygonal column shape, a conical shape, a polygonal pyramid shape, and the like.

  Further, in order to obtain the aluminum nickel mixed film 11 having a phase-separated structure as shown in FIG. 1, the ratio of nickel in the film needs to be 5 atomic% or more and 60 atomic% or less. Here, atomic% is the proportion of atoms contained in the film, and can be determined by quantitative analysis using, for example, ICP (inductively coupled plasma emission spectrometry).

Further, the diameter of cylinder-shaped aluminum nickel (Al ₃ Ni) and the distance between the cylinders vary from 5 nm to 300 nm in diameter by changing the composition of the entire film thickness that undergoes phase separation in the aluminum nickel mixed film. The center distance varies in the range of 20 nm to 500 nm.

  The film forming process of the aluminum nickel mixed film is not particularly limited as long as it can be formed on the substrate in a non-equilibrium state, and may be a sputtering method, for example. In the sputtering method, simultaneous sputtering of an aluminum target and a nickel target can be applied. Alternatively, several methods such as sputtering using a mixed target formed by sintering aluminum and nickel, or sputtering in which a nickel chip is disposed on an aluminum target can be applied. Note that the present invention is not limited to these methods.

  Further, by etching the structure schematically shown in FIG. 1, the aluminum portion of the matrix region 13 is selectively dissolved to form a convex portion (hereinafter referred to as a protrusion) as shown in FIG. ) 21 can be formed.

That is, in the manufacturing method of a mold having a convex-concave structure on a substrate, first, an aluminum nickel mixed film is formed in a non-equilibrium state on a nickel substrate. Second, a mixed film having a plurality of cylinders made of aluminum nickel (Al ₃ Ni) obtained by film formation and a matrix region surrounding the cylinder and made of aluminum (Al) as a component is obtained. Then, aluminum (Al) in the matrix region is selectively removed by etching with phosphoric acid or ammonia water. Thus, a mold made of nickel (Ni) or aluminum nickel (Al ₃ Ni) can be produced.

Further, in the case of the magnesium nickel mixed film, the structure shown in FIG. 1 is obtained in the same manner as the aluminum nickel mixed film.
A phase-separated mixed film 11 is formed in a plurality of cylinders 12 having cylindrical magnesium nickel (Mg ₂ Ni) as a component and a matrix region 13 having magnesium (Mg) as a component surrounding the cylinder. However, in this case, the ratio of nickel in the film needs to be 12 atomic% or more and 70 atomic% or less. At this time, the diameter and interval of the cylindrical magnesium formed are changed in the range of 10 nm to 300 nm in diameter and the interval in the range of 30 nm to 500 nm by changing the composition of the total thickness of the phase separation in the magnesium nickel mixed film. To do. As in the case of the aluminum nickel mixed film, a magnesium nickel mixed film is formed on the nickel substrate in a non-equilibrium state. And the metal mold | die consisting of nickel or a nickel alloy is producible by selectively etching away the magnesium (Mg) of a matrix area | region. In the case of the titanium nickel mixed film, the yttrium nickel mixed film, and the zirconium nickel mixed film, a mold made of nickel or a nickel alloy can be produced in the same manner as the aluminum nickel mixed film or magnesium.

  As described above, in the method for manufacturing a mold having a convex / concave structure on the substrate of the present invention, the matrix region is removed by etching. Thus, the concavo-convex structure having the convex protrusions 21 as shown in FIG. 2 is formed. However, it is also possible to form the concavo-convex structure having concave pores by etching away the cylinder portion. .

Next, the manufacturing method in the case of using an aluminum nickel mixed film is demonstrated about the manufacturing method of the metal mold | die which has a concave-convex structure on the board | substrate of this invention.
When the aluminum nickel mixed film is formed in a non-equilibrium state, a plurality of cylinders mainly composed of aluminum (Al) and a matrix region composed of aluminum nickel (Al ₃ Ni) surrounding the cylinders are phase-separated.

Growing in such a state, as shown in FIG. 1, a structure in which a cylindrical aluminum (Al) 12 portion is divided by a matrix region 13 of aluminum nickel (Al ₃ Ni) is formed. At this time, the shape of the cylindrical aluminum (Al) 12 includes a cylindrical shape, a polygonal column shape, a conical shape, a polygonal pyramid shape, and the like.

Similar to the above-described method for manufacturing a mold having a convex-concave structure on the substrate, the diameter of the cylindrical aluminum (Al) and the interval between the cylinders are as follows.
By changing the composition of the entire film thickness that undergoes phase separation in the aluminum nickel mixed film, the diameter changes in the range of 5 nm to 200 nm and the center interval distance ranges from 20 nm to 500 nm.

In addition, the film forming process of the aluminum nickel mixed film is not particularly limited as long as it can be formed on the substrate in a non-equilibrium state, and a sputtering method or the like may be used.
Further, by etching the structure schematically shown in FIG. 1, a plurality of cylinder portions 12 mainly composed of aluminum are selectively dissolved, and concave portions (hereinafter referred to as thin portions) as shown in FIG. It is possible to form a concavo-convex structure having 31).

That is, in the manufacturing method of a mold having a concave and convex structure on a substrate, first, an aluminum nickel mixed film is formed on a nickel substrate in a non-equilibrium state. Then, a mixed film having a plurality of cylinders made of aluminum (Al) obtained by film formation and a matrix region surrounding the cylinder and made of aluminum nickel (Al ₃ Ni) is obtained.

From this, aluminum (Al) in the cylinder portion is selectively removed by etching with phosphoric acid or aqueous ammonia, and a mold made of nickel (Ni) or aluminum nickel (Al ₃ Ni) can be produced.

  The material phase-separated from nickel can contain at least one of aluminum, magnesium, titanium, yttrium, and zirconium having a eutectic equilibrium diagram with nickel.

The matrix portion is removed from the mixed film containing nickel to form an uneven structure. A plurality of the concavo-convex structures are arranged on the substrate.
A mold including a concavo-convex structure made of nickel or a nickel alloy can be formed into a plurality of convex cylindrical concavo-convex structures.

  The ratio of the average diameter Dl in the major axis direction to the average diameter Ds in the minor axis direction in any one phase of the mixed film having a two-phase separation structure formed on the substrate may be 5 or more. Details will be described later.

  In the mixed film having a two-phase separation structure composed of the first and second columnar members as in the lamellar structure, it is also preferable to form the separation structure with one directionality and orientation. Details will be described later.

[Manufacturing Method 1 for Optical Element Mold]
The manufacturing method of the optical element mold according to the present invention will be described in the case of using a mixed film of nickel and a material having a eutectic equilibrium diagram and nickel. Examples of materials having an eutectic equilibrium diagram with nickel include the following materials.

  Aluminum (Al), magnesium (Mg), titanium (Ti), yttrium (Y), zirconium (Zr), and the like can be mentioned. The case where a mixed film of aluminum and nickel is used will be described in detail here. In order to manufacture an optical element capable of exhibiting the antireflection function on the entire optical surface of the optical element having a finite curvature, the following is performed.

In the mold for optical elements, the shape of a cylinder containing aluminum nickel (Al ₃ Ni) as a component (in the case of a die having protrusions), or the shape of a cylinder containing aluminum (Al) as a component (mold having pores) Control).

As described above, the composition of the entire film thickness to be phase-separated in the aluminum nickel mixed film is changed. Then, the ratio of nickel in the film is set to 5 atomic% or more and 60 atomic% or less. As a result, the diameter of the cylinder can be changed in the range of 5 nm to 300 nm and the center distance can be changed in the range of 20 nm to 500 nm. As a method of changing the composition of the entire film thickness for phase separation in the aluminum nickel mixed film, there is a method of laminating the aluminum nickel mixed film while gradually changing the film forming rate. Or the method of laminating | stacking an aluminum nickel mixed film using the target from which at least 2 or more types of composition ratios differ is mentioned. In the case of the sputtering method, the film formation rate can be changed by controlling film formation conditions such as input power, sputtering pressure, substrate bias, and substrate temperature. Thus, a cylindrical cylinder 42 of cylindrical aluminum nickel (Al ₃ Ni) shown in FIG. 4A is obtained. Furthermore, a structure in which the diameter continuously changes in the film thickness direction shown in FIG. 4B, that is, a conical aluminum nickel (Al ₃ Ni) cylinder 42 is formed (in the case of a mold having protrusions). .

That is, a cylindrical or conical aluminum nickel (Al ₃ Ni) cylinder is formed on the nickel substrate by the above method. Thereafter, an aluminum (Al) portion surrounding the cylinder portion is selectively etched away. As a result, a mold for an optical element having a concavo-convex structure of aluminum nickel (Al ₃ Ni) having a cylindrical or conical protrusion as shown in FIG. 5 can be produced.

Alternatively, a cylindrical or conical aluminum (Al) cylinder is formed on the nickel substrate by the above method. Then, the cylinder portion, that is, the aluminum (Al) portion is selectively removed by etching. Thus, an optical element mold having an uneven structure of aluminum nickel (Al ₃ Ni) having cylindrical or conical (not shown) pores as shown in FIG. 3 can be produced.

Furthermore, the aspect ratio of the concavo-convex structure, which is an element that determines the antireflection characteristic, and the volume ratio of the substrate to the atmosphere are as follows.
The depth of the concavo-convex structure (projection) of cylindrical or conical aluminum nickel (Al ₃ Ni) shown in FIG. 5 is preferably in the range of 100 nm to 500 nm. The cross-sectional area ratio at a half depth of the concavo-convex structure (protrusions) of the cylindrical or conical aluminum nickel (Al ₃ Ni) with respect to the nickel substrate is preferably in the range of 40% to 80%. (For molds with protrusions). Alternatively, the depth of the cylindrical or conical (not shown) concavo-convex structure (pores) shown in FIG. 3 is preferably in the range of 100 nm to 500 nm. The cross-sectional area ratio at a half depth of the cylindrical or conical concavo-convex structure (pores) with respect to the nickel substrate is preferably in the range of 30% or more and 70% or less (gold having pores). Type).

Here, the cross-sectional area ratio at 1/2 depth of the cylindrical or conical uneven structure (projection) of aluminum nickel (Al ₃ Ni) and the cylindrical or conical uneven structure (pore) is controlled. it can. Specifically, it can be controlled by a method of changing the composition of the entire film thickness to be phase-separated in the aluminum nickel mixed film, and the sputtering time is controlled in consideration of the film forming rate.

  Further, the concavo-convex structure according to the present invention is not limited to the cylindrical shape or the conical shape shown in FIGS. 3 and 5, and includes any shape realized by a combination of film forming conditions and composition ratios. It is.

Furthermore, the optical element mold of the present invention may have a structure as shown in FIG. 6 in which an adhesive layer 62 is provided between a nickel substrate and the aluminum nickel (Al ₃ Ni) cylinder. As the adhesive layer, titanium (Ti), nickel (Ni), and alloys containing them are preferable.

[Method 2 for producing mold for optical element]
The method for producing the mold for optical elements of the present invention will be described in the case of using a mixed film of nickel and a material that does not form a compound with nickel. Examples of the material that does not form a compound with nickel include silver (Ag) and gold (Au). Here, the case where a mixed film of gold and nickel is used will be described in detail. When gold and nickel are sputtered simultaneously in a non-equilibrium state, a plurality of cylinder parts mainly composed of nickel (Ni) (or gold (Au)) and gold (Au) (or nickel (Ni)) surrounding the cylinder are mainly used. Separate into matrix regions as components. At this time, the cylinder shape mainly composed of nickel (Ni) (or gold (Au)) is formed by crystal grain boundaries of crystallized nickel and gold, and a cylindrical shape, a polygonal column shape rather than a conical shape, It includes many polygonal pyramid shapes.

  Similarly to the above, in order to manufacture an optical element that can exhibit an antireflection function over the entire optical surface of an optical element having a finite curvature, nickel (Ni) (or gold) is used in the optical element mold. It is necessary to control the shape of the cylinder containing (Au)) as a component. The cylinder shape can be changed in the range of 10 nm to 100 nm in diameter and 30 nm to 500 nm in the interval by changing the composition ratio of nickel and gold in the gold-nickel mixed film. As a method of changing the composition ratio of nickel and gold in the gold-nickel mixed film, there is a method of laminating the gold-nickel mixed film while gradually changing the film forming rate. Or the method of laminating | stacking a gold-nickel mixed film using the target from which at least 2 or more types of composition ratios differ is mentioned. In the case of using a sputtering method, the film formation rate can be changed by controlling film formation conditions such as input power, sputtering pressure, substrate bias, and substrate temperature. By the method as described above, not only a cylindrical nickel (Ni) cylinder as shown in FIG. 4A but also a structure in which the diameter continuously changes in the film thickness direction is obtained. That is, a conical nickel (Ni) cylinder as shown in FIG. 4B is formed (in the case of a mold having protrusions).

  That is, a cylindrical or conical nickel (Ni) cylinder is formed on a nickel substrate by the above method, and a gold (Au) portion surrounding the cylinder portion is selectively etched away using a gold etching solution. . In this way, the optical element mold having the cylindrical or conical nickel (Ni) uneven structure shown in FIG. 5 can be produced.

  Alternatively, a cylindrical or conical gold (Au) cylinder is formed on the nickel substrate by the above method. The cylinder portion, that is, the gold (Au) portion is selectively etched away. In this manner, an optical element mold having a concavo-convex structure of nickel (Ni) having cylindrical or conical (not shown) pores as shown in FIG. 3 can be produced.

Furthermore, the following ranges are preferable for the aspect ratio of the concavo-convex structure, which is an element that determines the antireflection characteristics, and the volume ratio of the substrate to the atmosphere.
The depth of the cylindrical or conical nickel (Ni) uneven structure (projection) shown in FIG. 5 is in the range of 100 nm to 500 nm. The cross-sectional area ratio at a half depth of the concavo-convex structure (projection) of the cylindrical or conical gold nickel (Ni) with respect to the nickel substrate is preferably in the range of 40% or more and 80% or less (projection) For molds with Alternatively, the depth of the cylindrical or conical (not shown) concavo-convex structure (pores) shown in FIG. 3 is in the range of 100 nm to 500 nm. The cross-sectional area ratio at a half depth of the cylindrical or conical concavo-convex structure (pores) with respect to the nickel substrate is preferably in the range of 30% to 70% (having pores). For molds).

  Here, the cross-sectional area ratio at 1/2 depth of the cylindrical or conical concavo-convex structure (projections) of nickel (Ni) and the cylindrical or conical concavo-convex structure (pores) is as follows. Can be controlled.

  It can be controlled by a method of changing the composition ratio of gold and nickel in the gold-nickel mixed film as described above, and the desired uneven structure can be obtained by controlling the sputtering time in consideration of the film formation rate. Can be obtained.

  Further, the concavo-convex structure according to the present invention is not limited to the cylindrical shape or the conical shape shown in FIGS. 3 and 5, and may have any shape realized by a combination of film forming conditions and composition ratio. included.

  Further, the optical element mold according to the present invention may have a structure as shown in FIG. 6 in which an adhesive layer 63 is provided between a nickel substrate and the nickel (Ni) cylinder. Are preferably titanium (Ti), nickel (Ni), and alloys containing them.

In the above description, a mixed film of gold and nickel is described, but the present invention includes a mixed film of Ni and oxide. Examples of the oxide include MgO and SiO ₂ . In the method described in the production method 2, an oxide is used instead of silver or gold. The basic manufacturing method is the same as the manufacturing method 2 described above, but the substrate temperature during sputtering is preferably about 600 ° C.

The case where Ni and an oxide mixture are used will be described below.
[Method 3 for producing mold for optical element]
As for the method for producing a mold for optical elements of the present invention, a method for producing a mixed film of nickel and oxide will be described. Examples of the oxide material include silicon oxide (SiO ₂ ), magnesium oxide (MgO), and zinc oxide (ZnO). Here, the case where a mixed film of silicon oxide (SiO ₂ ) and nickel is used is described in detail. To state.

When silicon oxide (SiO ₂ ) and nickel are sputtered simultaneously in a non-equilibrium state, the result is as follows.
That is, it is divided into a plurality of cylinder portions mainly composed of nickel (or silicon oxide) and a matrix region mainly composed of silicon oxide (or nickel) surrounding the cylinder. At this time, the cylinder shape whose main component is nickel (Ni) (or silicon oxide (SiO ₂ )) is formed by crystal grain boundaries of crystallized nickel and gold, and is a polygonal column rather than a cylindrical shape or a conical shape. Many shapes and polygonal pyramid shapes are included.

Similarly to the above, in order to manufacture an optical element that can exhibit an antireflection function over the entire optical surface of an optical element having a finite curvature, it is necessary to control the shape. In other words, it is necessary to control the shape of the cylinder containing nickel (Ni) (or silicon oxide (SiO ₂ )) as a component in the optical element mold. The cylinder shape can be changed in the range of 10 nm to 100 nm in diameter and 30 nm to 500 nm in the interval by changing the composition ratio of nickel and silicon oxide (SiO ₂ ) in the silicon oxide-nickel mixed film. As a method of changing the composition ratio of nickel and silicon oxide in the silicon oxide-nickel mixed film, there are the following methods.

  Examples thereof include a method of laminating a silicon oxide-nickel mixed film while gradually changing the deposition rate, or a method of laminating a silicon oxide-nickel mixed film using at least two types of targets having different composition ratios. In the case of using a sputtering method, the film formation rate can be changed by controlling film formation conditions such as input power, sputtering pressure, substrate bias, and substrate temperature. By the method as described above, not only a cylindrical nickel (Ni) cylinder as shown in FIG. 4A but also a structure whose diameter continuously changes in the film thickness direction is formed. That is, a conical nickel (Ni) cylinder as shown in FIG. 4B is formed (in the case of a mold having protrusions).

That is, a cylindrical or conical nickel (Ni) cylinder is formed on the nickel substrate by the above method. Then, the silicon oxide (SiO ₂ ) portion surrounding the cylinder portion is selectively etched away using an alkaline etching solution. In this manner, the optical element mold having a columnar or conical nickel (Ni) microstructure shown in FIG. 5 can be produced.

Alternatively, a cylindrical or conical silicon oxide (SiO ₂ ) cylinder is formed on the nickel substrate by the above method, and the cylinder portion, that is, the silicon oxide (SiO ₂ ) portion is selectively etched away. By doing so, an optical element mold having a nickel (Ni) microstructure having cylindrical or conical (not shown) pores as shown in FIG. 3 can be produced.

  Further, regarding the aspect ratio of the microstructure and the volume ratio between the base material and the atmosphere, which are factors that determine the antireflection characteristic, the cylindrical or conical nickel (Ni) uneven structure (protrusion) shown in FIG. Is in the range of 100 nm to 500 nm. The cross-sectional area ratio at a half depth of the cylindrical or conical nickel (Ni) concavo-convex structure (projection) with respect to the nickel substrate is preferably in the range of 40% or more and 80% or less. If you have a mold). Alternatively, the depth of the columnar or conical (not shown) microstructure (pores) shown in FIG. 3 is preferably in the range of 100 nm to 500 nm. The cross-sectional area ratio at a half depth of the cylindrical or conical microstructure (pores) with respect to the nickel substrate is preferably within a range of 30% to 70% (having pores). For molds).

  Here, the cross-sectional area ratio at 1/2 depth of the columnar or conical nickel (Ni) microstructure (protrusion) and the columnar or conical microstructure (pore) can be controlled. Specifically, it can be controlled by a method of changing the composition ratio of nickel and silicon oxide in the nickel-silicon oxide mixed film as described above. In addition, by controlling the sputtering time in consideration of the film formation rate, a desired depth of the fine structure can be obtained.

  Further, the microstructure according to the present invention is not limited to the one having the columnar shape or the conical shape shown in FIGS. 3 and 5, and may have any shape realized by a combination of film forming conditions and composition ratios. included.

  Further, the optical element mold according to the present invention may have a structure as shown in FIG. 6 in which an adhesive layer 62 is provided between a nickel substrate and the nickel (Ni) cylinder. Are preferably titanium (Ti), nickel (Ni), and alloys containing them.

Examples according to the present invention will be described below.
Example 1
Example 1 relates to molding an optical element using a mold for an optical element having a concavo-convex structure of aluminum nickel having a convex shape (projection) on a nickel substrate.

  FIGS. 7A and 7B are schematic views schematically showing a cross section of an optical element obtained with the mold of the embodiment of the present invention. 7A shows the case where the base shape of the optical surface is a convex surface, and FIG. 7B shows the case where the base shape of the optical surface is a concave surface.

  7A and 7B, reference numeral 71 denotes an optical element (optical member) having a finite curvature (a finite curvature excluding infinity), and the base shape of the optical surface is formed as a convex surface or a concave surface. ing. The optical surface of the optical element 71 in the present embodiment is composed of a refractive surface, for example.

FIG. 8A is a schematic view schematically showing a cross section of a plurality of pores obtained by the mold of the embodiment of the present invention.
In the figure, 82 is a fine pore (concave portion), which has an antireflection function, and is provided in a plurality on a surface of the optical element 81 having a finite curvature (base shape is concave or convex) at random. ing. Each of the plurality of pores 82 has substantially the same concave shape, and is formed independently in the normal direction of the surface of the optical element 81.

  Here, the antireflection function refers to a function of reducing the reflectance of the surface on which the pores are arranged, preferably a reflectance of 1% or less, compared to the reflectance of the mirror surface. The concave shape refers to a shape in which a part is depressed, and includes, for example, a cylindrical shape, a conical shape, a polygonal column shape, a polygonal pyramid shape, and the like.

  The plurality of pores 82 include independent pores, but may include joined pores. The plurality of pores 82 are formed by molding on the surface of an optical element having a finite curvature.

  FIGS. 9A and 9B are schematic views schematically showing the arrangement of a plurality of pores obtained by the mold of the embodiment of the present invention. FIG. 6A shows the case of this example in which a plurality of pores 92 are randomly arranged on the surface of an optical element having a finite curvature, and FIG. The case where it arrange | positions in the shape of a triangular lattice on the surface of the optical element which has a finite curvature is shown.

  In this embodiment, when the center distance between adjacent pores 92 among the plurality of pores 92 is D and the wavelength to be used is λ,

Is set to satisfy the following conditions.
Here, the conditional expression (1) defines the upper limit of the center distance D between adjacent pores 92. That is, exceeding the upper limit of the conditional expression (1) is not preferable because it becomes difficult to develop an excellent antireflection characteristic on the entire optical surface. The lower limit is not limited in terms of function, and may be as small as possible as long as the volume ratio of pores and atmosphere described later is appropriate.

  The center distance D between adjacent pores refers to the center-to-center distance when approximately arranged in a triangular lattice shape. That is, as shown in FIG. 9 (A), for all the pores in the measurement region, the average of the center-to-center distances for the latest six pores is obtained, and the average value is calculated for the pores in the array. The distance between the centers.

  In this embodiment, a plurality of pores having substantially the same concave shape as described above are formed independently on the surface of the optical element having a finite curvature in the normal direction of the surface, thereby the optical surface. Uniform anti-reflective properties are expressed on the entire surface.

  In order to exhibit the antireflection function in the present embodiment, it is particularly preferable that the interval between adjacent pores is ½ or less of the design wavelength λ of the optical element that is said not to generate zero-order diffracted light. is there.

Therefore, in this embodiment, the antireflection function is exhibited by setting the center distance D between adjacent pores so as to satisfy the conditional expression (1).
Here, the design wavelength refers to the wavelength of light that is transmitted through or reflected by the optical element, and refers to a wavelength that is intended to suppress the amount of reflected light. For example, when it is desired to transmit visible light through an optical element and suppress the amount of reflected light having a wavelength of 600 nm or less, the design wavelength is regarded as 600 nm, and the interval between adjacent pores is preferably 300 nm or less. Alternatively, the laser beam printer exemplified in the above-described problem uses laser light of 780 nm or less, and the interval between adjacent pores is preferably 390 nm or less.

  In the present embodiment, as described above, the plurality of concave pores are randomly arranged on the surface of the optical element having a finite curvature. That is, when there is a certain regularity when arranging the pores, there is an advantage of obtaining a sharp antireflection characteristic with respect to the wavelength, but there is a possibility that the optical characteristic has an angle dependency. For example, when regularly orthogonally arranged in a grid pattern, the gap between the pores is the shortest along the arrangement and the longest in the direction of 45 degrees, so that the optical characteristics depend on the incident direction of light. Will shift.

Therefore, in this embodiment, in order to obtain stable optical characteristics regardless of the incident direction of light, a plurality of concave pores are randomly arranged.
In general, when two substances having different refractive indexes with a pitch shorter than the wavelength are mixed, the refractive index n12 of the mixed area occupies the refractive index (n1, n2) of the two substances and per unit volume. By each volume (ff1, ff2), it can represent with following Formula (2).

  At this time, when only two substances exist in the mixed area,

In the case where light is incident vertically from the substance 1 to the substance 2 or from the substance 2 to the substance 1, the equivalent refractive index n12 of the mixed region is

When it is, the antireflection effect becomes the highest.
For example, when the pores are filled with air, the unit volume of the pores that has the highest antireflection effect when the refractive index of the substance constituting the pore walls (aluminum nickel in this embodiment) is n. The ratio ff per unit is expressed by the following equation (5).

  If the optical surface on which the pores are formed is the outermost surface in contact with the atmosphere, and the refractive index n of the material constituting the walls of the pores is 1.56, to obtain the maximum antireflection effect for normal incidence It is particularly preferable that the volume ratio occupied by the pores is approximately 56% from the formula (5). Further, the optimum value of the volume ratio is appropriately set according to the incident angle and polarization of light as well as the refractive index of the material constituting the pore wall, but empirically the volume ratio is 35% to 62%. It is particularly preferable that the pores are formed in order to obtain desired antireflection properties.

  As described above, in this embodiment, by providing a plurality of concave pores having an antireflection function on the surface of the optical element having the finite curvature as described above, the antireflection characteristic is uniform over the entire optical surface. Is expressed.

Example 2
Example 2 relates to molding an optical element by using a mold for an optical element having a concave and convex structure of aluminum aluminum having a concave shape on a nickel substrate.

FIG. 8B is a schematic view schematically showing a cross section of a plurality of pores obtained by the mold according to the embodiment of the present invention.
83 in the figure is a fine protrusion (convex shape portion), which has an antireflection function and is randomly provided on the surface of the optical element 81 having a finite curvature (base shape is concave or convex). Yes. Each of the plurality of protrusions 83 has substantially the same convex shape, and is formed independently in the normal direction of the surface of the optical element 81.

  Here, the antireflection function refers to a function of reducing the reflectance of the surface on which the protrusions are arranged as compared to the reflectance of the mirror surface, and preferably the reflectance is 1% or less. Further, the convex shape refers to a shape in which a part projects, and includes, for example, a cylindrical shape, a conical shape, a polygonal column shape, a polygonal pyramid shape, and the like.

  In addition, although the some protrusion 83 contains the independent protrusion, you may include the joined protrusion. The plurality of protrusions 83 are formed by molding on the surface of the optical element having a finite curvature.

  FIGS. 9A and 9B are schematic views schematically showing the arrangement of a plurality of pores (Example 1) or protrusions (Example 2) obtained by the mold of the example of the present invention. . 9A shows the case of this example in which a plurality of protrusions 92 are randomly arranged on the surface of an optical element having a finite curvature, and FIG. 9B shows the case of FIG. The case where the protrusions 92 are arranged in a triangular lattice pattern on the surface of the optical element having a finite curvature is shown.

  In this embodiment, when the center distance between adjacent protrusions 92 among the plurality of protrusions 92 is D, and the wavelength to be used is λ,

Is set to satisfy the following conditions.
Here, the conditional expression (6) defines the upper limit of the center distance D between the adjacent protrusions 92. That is, exceeding the upper limit of the conditional expression (6) is not preferable because it becomes difficult to develop an excellent antireflection characteristic on the entire optical surface. Moreover, there is no functional limitation on the lower limit, and the lower limit may be small as long as the volume ratio between the protrusion and the atmosphere is appropriate.

  The center distance D between adjacent protrusions refers to the distance between the centers when approximately arranged in a triangular lattice shape. That is, as shown in FIG. 9A, for all the pores in the measurement region, the average of the distances between the centers of the six most recent projections is obtained, and the average value is calculated between the centers of the projections in the array. Distance.

  In the present embodiment, a plurality of projections having substantially the same convex shape as described above are formed independently on the surface of the optical element having a finite curvature in the normal direction of the surface, whereby the entire surface of the optical surface is formed. It exhibits uniform antireflection characteristics.

  In order to exhibit the antireflection function in the present embodiment, it is particularly preferable that the interval between the adjacent protrusions is ½ or less of the design wavelength λ of the optical element that is said not to generate zero-order diffracted light. .

Therefore, in this embodiment, the antireflection function is exhibited by setting the center distance D between adjacent protrusions so as to satisfy the conditional expression (6).
Here, the design wavelength refers to the wavelength of light that is transmitted through or reflected by the optical element, and refers to a wavelength that is intended to suppress the amount of reflected light. For example, when it is desired to transmit visible light through an optical element and suppress the amount of reflected light having a wavelength of 600 nm or less, the design wavelength is regarded as 600 nm, and the interval between adjacent protrusions is preferably 300 nm or less. Alternatively, in the laser beam printer exemplified in the above-described problem, a laser beam having a wavelength of 780 nm or less is used, and the interval between adjacent protrusions is preferably 390 nm or less.

  In this embodiment, as described above, a plurality of convex protrusions are randomly arranged on the surface of the optical element having a finite curvature. That is, when a certain regularity is provided when the protrusions are arranged, there is an advantage of obtaining an antireflection characteristic that is sharp with respect to the wavelength, but there is a risk that the optical characteristic may be angularly dependent. For example, in the case of regular orthogonal arrangement in a grid pattern, the distance between the protrusions is the shortest along the arrangement and the longest in the direction of 45 degrees, so the optical characteristics shift depending on the incident direction of light. Will do.

Therefore, in this embodiment, in order to obtain stable optical characteristics without depending on the incident direction of light, convex protrusions are randomly arranged.
At this time, as in the first embodiment, the antireflection characteristic can be described as follows.

  In general, when two substances having different refractive indexes with a pitch shorter than the wavelength are mixed, the refractive index n12 of the mixed area occupies the refractive index (n1, n2) of the two substances and per unit volume. By each volume (ff1, ff2), it can represent with following Formula (7).

  At this time, when only two substances exist in the mixed area,

In the case where light is incident vertically from the substance 1 to the substance 2 or from the substance 2 to the substance 1, the equivalent refractive index n12 of the mixed region is

When it is, the antireflection effect becomes the highest.
For example, when the projections are filled with air, and the refractive index of the substance constituting the projection walls (aluminum nickel in this embodiment) is n, the ratio of the projections per unit volume with the highest antireflection effect ff is expressed by the following equation (10).

  If the optical surface on which the protrusion is formed is the outermost surface in contact with the atmosphere, and the refractive index n of the material constituting the protrusion wall is 1.56, in order to obtain the maximum antireflection effect for normal incidence, From the formula (10), it is particularly preferable that the volume ratio occupied by the protrusions is approximately 44%. Further, the optimum value of the volume ratio is appropriately set according to the incident angle and polarization of light as well as the refractive index of the material constituting the wall of the protrusion, but empirically, the volume ratio is 38% or more and 65% or less. It is particularly preferable to form the protrusions in order to obtain desired antireflection characteristics.

  As described above, in this embodiment, by providing a plurality of convex protrusions having an antireflection function on the surface of the optical element having the finite curvature as described above, a uniform antireflection characteristic is provided on the entire optical surface. It is expressed.

Next, the manufacturing method of the optical element of this invention is demonstrated.
In addition, the manufacturing method of this invention is not limited to the manufacturing method shown below. In the present invention, the antireflection of a 780 nm P-polarized laser is targeted. However, the antireflection characteristic of the optical element obtained by the present invention is not limited to a single wavelength laser, and visible light, ultraviolet light, infrared light. It is applicable to.

  In the present invention, a mold for an optical element having a concavo-convex structure of nickel or a nickel alloy having a columnar or conical protrusion formed from a material phase-separated from nickel and a structure obtained by a film forming process of nickel The manufacturing process is performed. Thereafter, an optical element is formed using an element forming step of forming pores by transferring the protrusions using the mold.

  Alternatively, an optical element mold having a concavo-convex structure of nickel or a nickel alloy having a cylindrical or conical pore formed from a material obtained by a film forming process of nickel and a material phase-separated from nickel. Perform the manufacturing process. Then, an optical element is formed using an element forming step of forming protrusions by transferring the pores using the mold.

  As described in [Manufacturing method of mold for optical element], the period and the hole diameter of cylindrical or conical protrusions (or pores) can be controlled by appropriately selecting conditions.

  That is, by appropriately selecting the film forming conditions by the sputtering method, desired protrusions (or pores) can be formed all over the mold surface, and SWS can be formed in a short time and at low cost. Is possible.

  In addition, as a means for transferring the protrusions (or pores) formed on the mold, any molding means such as injection, replica, press, casting, etc. may be used. Molding is particularly suitable. Moreover, when releasing from a metal mold | die, the direction of a processus | protrusion (or pore) and the mold release direction are not necessarily parallel. However, while the pores (or projections) formed by transferring the projections (or pores) can tolerate some deformation, for example, the mold can be easily released by releasing before the pores completely solidify. Can do.

[Optical Element Manufacturing Method 1]
The optical element manufacturing method 1 according to the first embodiment relates to molding an optical element using a mold for an optical element having a cylindrical aluminum nickel uneven structure (projection) on a nickel substrate.

The optical element manufacturing method 1 will be described.
First, a mold having a free curved surface for forming an fθ lens (optical element) was prepared, and a primer layer and an aluminum nickel layer were uniformly formed on the free curved surface in this order by sputtering and covered with an aluminum nickel mixed film. A mold having a curved surface was obtained. Here, the aluminum nickel mixed film was formed by a magnetron sputtering method using an RF power source. The target used was a nickel chip (1.5 cm square) disposed on an aluminum target having a diameter of 4 inches (50.8 mm). The film formation was performed under the conditions that the input power was RF 40 W, the argon gas pressure was 0.11 Pa, the substrate temperature was 300 ° C., and the film was formed to a desired film thickness. FIG. 4A is a diagram schematically showing a cross-sectional image of an aluminum nickel mixed film observed with an FE-SEM (field emission scanning electron microscope). In the formed aluminum nickel mixed film 41, an aluminum nickel (Al ₃ Ni) portion 42 is formed in a cylinder shape perpendicular to the nickel substrate 40. It was confirmed that an aluminum matrix region 43 surrounding the aluminum nickel (Al ₃ Ni) portion 42 was formed. Then, the entire mold is covered with a masking tape so that only the free curved surface is exposed, and the other curved surface is insulated and waterproofed by coating, and immersed in an aqueous phosphoric acid solution at room temperature. In this way, aluminum surrounding the aluminum nickel (Al ₃ Ni) portion was dissolved to obtain a fθ mold having aluminum nickel (Al ₃ Ni) protrusions on the mold surface.

When the mold for the fθ lens thus obtained was observed with an FE-SEM (Field Emission Scanning Electron Microscope), innumerable protrusions in a random array were standing perpendicular to the mold surface. When the center coordinate position of the protrusion was obtained by image processing and the center distance D between the six adjacent pores was obtained, the center distance D between the adjacent pores was a period of about 300 nm. The mold manufactured by the above procedure is placed on the entrance surface side and the exit surface side of an injection molding machine (Sumitomo Heavy Industries, Ltd .: SS180), and a cycloolefin polymer (Nippon Zeon Corporation) is injection molded to produce an fθ lens. Got. At this time, the molten resin temperature was set to 270 ° C., and the holding pressure at the time of resin injection was set to 700 kg / cm ² .

  When the fθ lens thus obtained was observed with an FE-SEM (field emission scanning electron microscope), columnar pores randomly arranged over the entire curved surface were observed, and each columnar pore was a surface. It was confirmed that it was formed toward the normal direction.

  Further, the center position of the pores was obtained by image processing, and the average of the center distances D between the six adjacent columnar pores was obtained. The center distance D between the adjacent pores was about 300 nm. Yes, it was confirmed that the protrusions of the mold were transferred.

  Further, when the height of the columnar pores was measured with an atomic force microscope, the thickness of the pores was almost uniform toward the tip, the average depth was about 160 nm, and the volume ratio of the pores was about 44. %Met. Therefore, when the reflectance at the time of perpendicular incidence of P-polarized light was measured using a spectrophotometer, it was 0.7%.

[Optical Element Manufacturing Method 2]
The optical element manufacturing method 2 according to this example relates to molding an optical element by using a mold for an optical element having a concavity and convexity structure (projection) of conical aluminum nickel on a nickel substrate.

The optical element manufacturing method 2 will be described.
Similar to the optical element manufacturing method 1, first, a mold having a free curved surface for forming an fθ lens (optical element) was prepared, and a mold having a free curved surface covered with an aluminum nickel mixed film was obtained by sputtering. Here, as in the optical element manufacturing method 1, the aluminum nickel mixed film was formed by magnetron sputtering using an RF power source. The target used is a nickel chip (1.5 cm square) placed on an aluminum target having a diameter of 4 inches (101.6 mm). Three types (target A, target B, target C) having different numbers of nickel chips arranged on the aluminum target were prepared. The ratio of nickel in the film was A>B> C. First, using the target A, a film was formed for 10 minutes at an input power of RF 40 W, an argon gas pressure of 0.11 Pa, and a substrate temperature of 300 ° C. Next, after the input power to the target A was cut off, a film was formed using the target B for 10 minutes at an input power of RF 40 W, an argon gas pressure of 0.11 Pa, and a substrate temperature of 300 ° C. After cutting off the input power to the target B, the film was finally formed using the target C at an input power of RF 40 W, an argon gas pressure of 0.11 Pa, and a substrate temperature of 300 ° C. for 10 minutes. After the film formation was completed, the surface and cross-sectional shape of the aluminum nickel mixed film were observed with an FE-SEM (field emission scanning electron microscope). FIG. 4B is a diagram schematically showing a cross-sectional image of the aluminum nickel mixed film observed with an FE-SEM (field emission scanning electron microscope). In the formed aluminum nickel mixed film 41, an aluminum nickel (Al ₃ Ni) portion 42 is formed in a cylinder shape perpendicular to the nickel substrate 40. It was confirmed that an aluminum matrix region 43 surrounding the aluminum nickel (Al ₃ Ni) portion 42 was formed. Further, the diameter of the aluminum nickel (Al ₃ Ni) cylinder portion 42 was continuously changed depending on the target having a different composition ratio of aluminum nickel. As a result, it was confirmed that the diameter gradually decreased with increasing distance from the substrate, that is, a conical aluminum nickel (Al ₃ Ni) cylinder portion 42 was formed.

Then, the entire mold was covered with a masking tape so that only the free curved surface was exposed, and other than the free curved surface was insulated and waterproofed by coating, and immersed in an aqueous phosphoric acid solution at room temperature. As a result, the aluminum surrounding the aluminum nickel (Al ₃ Ni) portion was dissolved to obtain an fθ mold having aluminum nickel (Al ₃ Ni) protrusions on the mold surface.

  When the mold for the fθ lens thus obtained was observed with an FE-SEM (Field Emission Scanning Electron Microscope), innumerable protrusions of random arrangement were standing perpendicular to the mold surface. When the center coordinate position of the projection was obtained by image processing and the center distance D between the six adjacent pores was obtained, the center distance D between the adjacent pores was a period of about 240 nm.

The mold manufactured by the above procedure is placed on the entrance surface side and the exit surface side of an injection molding machine (Sumitomo Heavy Industries, Ltd .: SS180), and a cycloolefin polymer (Nippon Zeon Corporation) is injection molded to produce an fθ lens. Got. At this time, the molten resin temperature was set to 270 ° C., and the holding pressure at the time of resin injection was set to 700 kg / cm ² .

  When the fθ lens thus obtained was observed with an FE-SEM (field emission scanning electron microscope), columnar pores randomly arranged over the entire curved surface were observed, and each columnar pore was a surface. It was confirmed that it was formed toward the normal direction.

  Further, the center position of the pores is obtained by image processing, and the average of the center distances D between the six adjacent columnar pores is obtained. The center distance D between the adjacent pores is about 240 nm. Yes, it was confirmed that the protrusions of the mold were transferred.

  Further, when the height of the columnar pores was measured with an atomic force microscope, the thickness of the pores was almost uniform toward the tip, the average depth was about 180 nm, and the volume ratio of the pores was about 46. %Met. Therefore, when the reflectance at the time of perpendicular incidence of P-polarized light with a wavelength of 780 nm was measured using a spectrophotometer, it was 0.6%.

[Optical Element Manufacturing Method 3]
The optical element manufacturing method 3 according to Example 2 relates to molding an optical element using an optical element mold made of aluminum nickel having a cylindrical uneven structure (pores) on a nickel substrate.

The optical element manufacturing method 3 will be described.
First, a mold having a free curved surface for forming an fθ lens (optical element) was prepared, and a primer layer and an aluminum nickel layer were uniformly formed on the free curved surface in this order by sputtering and covered with an aluminum nickel mixed film. A mold having a curved surface was obtained. Here, the aluminum nickel mixed film was formed by a magnetron sputtering method using an RF power source. The target used was a 4 inch (101.6 mm) diameter aluminum target with a nickel chip (1.5 cm square) arranged. The film formation was performed under the conditions that the input power was RF 40 W, the argon gas pressure was 0.11 Pa, the substrate temperature was 300 ° C., and the film was formed to a desired film thickness. FIG. 4A is a diagram schematically showing a cross-sectional image of an aluminum nickel mixed film observed with an FE-SEM (field emission scanning electron microscope). In the formed aluminum nickel mixed film 41, an aluminum (Al) portion 42 is formed in a cylinder shape perpendicular to the nickel substrate 40. It was confirmed that an aluminum nickel (Al ₃ Ni) matrix region 43 surrounding the aluminum (Al ₃ ) portion 42 was formed. Then, the entire mold was covered with a masking tape so that only the free curved surface was exposed, and other than the free curved surface was insulated and waterproofed by coating, and immersed in an aqueous phosphoric acid solution at room temperature. Thus, the aluminum cylinder surrounded by the aluminum nickel (Al ₃ Ni) portion was melted to obtain a fθ mold made of aluminum nickel (Al ₃ Ni) having cylindrical pores on the mold surface.

When the mold for the fθ lens thus obtained was observed with an FE-SEM (Field Emission Scanning Electron Microscope), innumerable pores of random arrangement were standing perpendicular to the mold surface. The center coordinate position of the pores was obtained by image processing, and the center-to-center distance D between six adjacent pores was obtained. The center-to-center distance D between adjacent pores was a period of about 300 nm. . The mold manufactured by the above procedure is placed on the entrance surface side and the exit surface side of an injection molding machine (Sumitomo Heavy Industries, Ltd .: SS180), and a cycloolefin polymer (Nippon Zeon Corporation) is injection molded to produce an fθ lens. Got. At this time, the molten resin temperature was set to 270 ° C., and the holding pressure at the time of resin injection was set to 700 kg / cm ² .

  When the fθ lens thus obtained was observed with an FE-SEM (field emission scanning electron microscope), columnar protrusions randomly arranged over the entire curved surface were observed, and the individual columnar protrusions were normal to the surface. It was confirmed that it was formed in the direction.

  In addition, when the center position of the protrusion is obtained by image processing and the average of the distances D between the centers of the six adjacent columnar protrusions is obtained, the distance D between the centers of the adjacent protrusions is approximately 300 nm. It was confirmed that the pores of the mold were transferred.

  Further, when the height of the columnar projections was measured with an atomic force microscope, the thickness of the projections was almost uniform toward the tip, the average depth was about 160 nm, and the volume ratio of the pores was about 54%. there were. Therefore, the reflectance at the time of vertical incidence of P-polarized light with a wavelength of 780 nm was measured using a spectrophotometer and found to be 1.4%.

[Optical Element Manufacturing Method 4]
The optical element manufacturing method 4 according to the second embodiment relates to molding an optical element using an optical element mold made of aluminum nickel having a conical uneven structure (projection) on a nickel substrate.

The optical element manufacturing method 4 will be described.
Similar to the optical element manufacturing method 3, first, a mold having a free curved surface for forming an fθ lens (optical element) was prepared, and a mold having a free curved surface covered with an aluminum nickel mixed film was obtained by sputtering. Here, similarly to the optical element manufacturing method 3, the aluminum nickel mixed film was formed by a magnetron sputtering method using an RF power source. The target used is a nickel chip (1.5 cm square) placed on an aluminum target having a diameter of 4 inches (101.6 mm). Three types (target A, target B, target C) having different numbers of nickel chips arranged on the aluminum target were prepared. The ratio of nickel in the film was A>B> C. First, using the target A, a film was formed for 10 minutes at an input power of RF 40 W, an argon gas pressure of 0.11 Pa, and a substrate temperature of 300 ° C. Next, after the input power to the target A was cut off, a film was formed using the target B for 10 minutes at an input power of RF 40 W, an argon gas pressure of 0.11 Pa, and a substrate temperature of 300 ° C. After cutting off the input power to the target B, the film was finally formed using the target C at an input power of RF 40 W, an argon gas pressure of 0.11 Pa, and a substrate temperature of 300 ° C. for 10 minutes. After the film formation was completed, the surface and cross-sectional shape of the aluminum nickel mixed film were observed with an FE-SEM (field emission scanning electron microscope). FIG. 4B is a diagram schematically showing a cross-sectional image of the aluminum nickel mixed film observed with an FE-SEM (field emission scanning electron microscope). In the formed aluminum nickel mixed film 41, an aluminum (Al) portion 42 is formed in a cylinder shape perpendicular to the nickel substrate 40. It was confirmed that an aluminum nickel (Al ₃ Ni) matrix region 43 surrounding the aluminum (Al) portion 42 was formed. In addition, as a result of film formation by continuously changing the diameter of the aluminum (Al) cylinder portion 42 using targets having different composition ratios of aluminum nickel, the diameter gradually decreases as the distance from the substrate increases. That is, it was confirmed that a conical aluminum (Al) cylinder portion 42 was formed.

Then, the entire mold is covered with a masking tape so that only the free curved surface is exposed, the other curved surfaces are insulated and waterproofed by coating, and immersed in an aqueous phosphoric acid solution at room temperature. Thus, the aluminum cylinder surrounded by the aluminum nickel (Al ₃ Ni) portion was melted to obtain a fθ mold made of aluminum nickel (Al ₃ Ni) having conical pores on the mold surface.

  The mold for the fθ lens thus obtained was observed with an FE-SEM (field emission scanning electron microscope). Innumerable pores of random arrangement are standing perpendicular to the mold surface, and the center coordinate position of the pores is obtained by image processing, and the distance D between the centers of 6 adjacent pores is obtained. The center-to-center distance D between adjacent pores was about 240 nm.

The mold manufactured by the above procedure is placed on the entrance surface side and the exit surface side of an injection molding machine (Sumitomo Heavy Industries, Ltd .: SS180), and a cycloolefin polymer (Nippon Zeon Corporation) is injection molded to produce an fθ lens. Got. At this time, the molten resin temperature was set to 270 ° C., and the holding pressure at the time of resin injection was set to 700 kg / cm ² .

  When the fθ lens thus obtained was observed with an FE-SEM (field emission scanning electron microscope), columnar protrusions randomly arranged over the entire curved surface were observed, and the individual columnar protrusions were normal to the surface. It was confirmed that it was formed in the direction.

  In addition, when the center position of the protrusion is obtained by image processing and the average of the distances D between the centers of the six adjacent columnar protrusions is obtained, the distance D between the centers of the adjacent protrusions is approximately 240 nm. It was confirmed that the pores of the mold were transferred.

  Further, when the height of the columnar pores was measured with an atomic force microscope, the thickness of the pores was almost uniform toward the tip, the average depth was about 180 nm, and the volume ratio of the pores was about 52. %Met. Therefore, the reflectance at the time of perpendicular incidence of P-polarized light with a wavelength of 780 nm was measured using a spectrophotometer and found to be 1.2%.

Comparative Example 1
Next, a comparative example for manufacturing method 1 and manufacturing method 2 will be described.
A mold having a free curved surface for molding an fθ lens (optical element) was prepared, and injection molding was performed in the same manner as in Manufacturing Method 1 and Manufacturing Method 2. As a result, an fθ lens having a free curved mirror surface was obtained.

  When the optical element thus obtained was observed with a scanning electron microscope, only a smooth surface was observed. The reflectance at the time of vertical incidence of P-polarized light with a wavelength of 780 nm was measured with a spectrophotometer. %Met.

[Optical equipment]
The optical element of the present invention can be applied to imaging devices such as cameras and video cameras, or projection devices such as liquid crystal projectors and displays, and optical scanning devices for electrophotographic devices. For example, in an optical scanning device of an electrophotographic apparatus, good reflection characteristics can be obtained if an fθ lens having a plurality of pores formed on both the incident surface and the incident / exit surface of the fθ lens constituting the conjugating optical means is mounted.

[Optical scanning device]
FIG. 10 is a schematic view of the main part when the fθ lens including the optical element manufactured by the manufacturing method 1 is applied to the imaging optical means of an optical scanning device such as an electrophotographic apparatus.

  In the figure, reference numeral 1 denotes a light source means (semiconductor laser), which comprises, for example, a single beam laser or a multi-beam laser. Reference numeral 2 denotes a collimator lens, which converts a light beam emitted from the light source means 1 into a substantially parallel light beam. Reference numeral 3 denotes an aperture stop which shapes the beam shape by limiting the passing light flux. A cylindrical lens 4 has a predetermined power only in the sub-scanning direction, and the light beam that has passed through the aperture stop 3 is substantially applied to a deflection surface (reflection surface) 5a of an optical deflector 5 to be described later in the sub-scan section. It is formed as a line image.

  An optical deflector 5 as a deflecting means is composed of, for example, a four-sided polygon mirror (rotating polygon mirror), and is rotated at a constant speed in the direction of arrow A in the figure by a driving means (not shown) such as a motor. ing.

  Reference numeral 6 denotes an fθ lens system as an imaging optical means having a condensing function and an fθ characteristic, and the first and second fθ lenses 6a manufactured by any one of the manufacturing methods 1 to 4 described above, 6b. A plurality of pores 12 are formed on the entrance and exit surfaces 6a1, 6a2, 6b1, and 6b2 of the first and second fθ lenses 6a and 6b. A light beam based on the image information reflected and deflected by the optical deflector 5 is imaged on the photosensitive drum surface 7 as a surface to be scanned, and the deflection surface 5a of the optical deflector 5 and the photosensitive drum surface 7 in the sub-scanning section. Is in a conjugate relationship. Thus, the tilt correction function is provided.

Reference numeral 7 denotes a photosensitive drum surface as a surface to be scanned.
In this embodiment, the light beam emitted from the semiconductor laser 1 is converted into a substantially parallel light beam by the collimator lens 2, the light beam (light quantity) is limited by the aperture stop 3, and is incident on the cylindrical lens 4. Of the substantially parallel light beam incident on the cylindrical lens 4, the light beam is emitted as it is in the main scanning section. In the sub-scan section, the light beam converges and forms a substantially linear image (a linear image long in the main scanning direction) on the deflecting surface 5a of the optical deflector 5. The light beam reflected and deflected by the deflecting surface 5a of the optical deflector 5 is imaged in a spot shape on the photosensitive drum surface 7 via the first and second fθ lenses 6a and 6b. By rotating the optical deflector 5 in the direction of arrow A, the photosensitive drum surface 7 is optically scanned in the direction of arrow B (main scanning direction) at a constant speed. As a result, an image is recorded on the photosensitive drum surface 7 as a recording medium.

  With the above configuration, high luminance and energy saving can be realized by suppressing the amount of reflected light on the incident surface of the fθ lens (optical element) to prevent problems such as ghosts or increasing the amount of transmitted light on the exit surface. Furthermore, the above configuration makes it possible to use an inexpensive fθ lens having an antireflection function, and in particular, in an optical apparatus equipped with a plurality of the same elements, the cost can be reduced according to the number.

  In the optical scanning device described above, the plurality of pores 12 are formed on the entrance surfaces and exit surfaces 6a1, 6a2, 6b1, and 6b2 of the first and second fθ lenses 6a and 6b. Not only this but one f (theta) lens may be sufficient, and it may be not only both surfaces of an incident surface and an output surface but one surface.

[Image forming apparatus]
FIG. 11 is a cross-sectional view of the principal part in the sub-scanning direction showing an embodiment of the image forming apparatus of the present invention using the optical scanning device having the configuration shown in FIG. In FIG. 11, reference numeral 104 denotes an image forming apparatus. Code data Dc is input to the image forming apparatus 104 from an external device 117 such as a personal computer. The code data Dc is converted into image data (dot data) Di by a printer controller 111 in the apparatus. The image data Di is input to the optical scanning device 100 having the configuration shown in FIG. The light scanning device 100 emits a light beam 103 modulated in accordance with the image data Di, and the light beam 103 scans the photosensitive surface of the photosensitive drum 101 in the main scanning direction.

  The photosensitive drum 101 serving as an electrostatic latent image carrier (photoconductor) is rotated clockwise by a motor 115. With this rotation, the photosensitive surface of the photosensitive drum 101 moves in the sub-scanning direction perpendicular to the main scanning direction with respect to the light beam 103. Above the photosensitive drum 101, a charging roller 102 for uniformly charging the surface of the photosensitive drum 101 is provided so as to contact the surface. The surface of the photosensitive drum 101 charged by the charging roller 102 is irradiated with a light beam 103 scanned by the optical scanning device 100.

  As described above, the light beam 103 is modulated based on the image data Di, and by irradiating the light beam 103, an electrostatic latent image is formed on the surface of the photosensitive drum 101. The electrostatic latent image is developed as a toner image by a developing unit 107 disposed so as to contact the photosensitive drum 101 further downstream in the rotation direction of the photosensitive drum 101 than the irradiation position of the light beam 103.

  The toner image developed by the developing unit 107 is transferred onto a sheet 112 as a transfer material by a transfer roller 108 disposed below the photosensitive drum 101 so as to face the photosensitive drum 101. The paper 112 is stored in the paper cassette 109 in front of the photosensitive drum 101 (on the right side in FIG. 5), but can be fed manually. A paper feed roller 110 is provided at the end of the paper cassette 109, and feeds the paper 112 in the paper cassette 109 into the transport path.

  As described above, the sheet 112 on which the unfixed toner image has been transferred is further conveyed to the fixing device behind the photosensitive drum 101 (left side in FIG. 11). The fixing device includes a fixing roller 113 having a fixing heater (not shown) therein and a pressure roller 114 disposed so as to be in pressure contact with the fixing roller 113. The unfixed toner image on the sheet 112 is fixed by heating the sheet 112 conveyed from the transfer unit while being pressed by the pressure contact portion between the fixing roller 113 and the pressure roller 114. Further, a paper discharge roller 116 is disposed behind the fixing roller 113, and the fixed paper 112 is discharged out of the image forming apparatus.

  Although not shown in FIG. 5, the print controller 111 controls not only the data conversion described above, but also controls each part in the image forming apparatus including the motor 115, a polygon motor in the optical scanning apparatus described later, and the like. I do.

  When this image forming apparatus was used to repeatedly output a pattern image and a photographic image, no ghost phenomenon occurred and there was no problem in durability.

[Color image forming apparatus]
FIG. 12 is a schematic view of a main part of a color image forming apparatus according to an embodiment of the present invention using a plurality of optical scanning devices having the configuration shown in FIG. This embodiment is a tandem type color image forming apparatus in which four optical scanning devices are arranged side by side and image information is recorded on a photosensitive drum surface as an image carrier in parallel. In FIG. 12, reference numeral 160 denotes a color image forming apparatus, and 161, 162, 163 and 164 denote optical scanning apparatuses each having the configuration shown in FIG. Reference numerals 121, 122, 123, and 124 denote photosensitive drums as image carriers, 131, 132, 133, and 134 denote developing units, and 151 denotes a conveyance belt.

  In FIG. 12, the color image forming apparatus 160 receives R (red), G (green), and B (blue) color signals from an external device 152 such as a personal computer. These color signals are converted into C (cyan), M (magenta), Y (yellow), and B (black) image data (dot data) by a printer controller 153 in the apparatus. These image data are input to the optical scanning devices 161, 162, 163, and 164, respectively. From these optical scanning devices, light beams 141, 142, 143, and 144 modulated according to each image data are emitted, and the photosensitive surfaces of the photosensitive drums 121, 122, 123, and 124 are emitted by these light beams. Scanned in the main scanning direction.

  In the color image forming apparatus according to the present embodiment, four optical scanning devices (161, 162, 163, 64) are arranged. Each corresponds to each color of C (cyan), M (magenta), Y (yellow), and B (black), and image signals (image information) are respectively formed on the surfaces of the photosensitive drums 121, 122, 123, and 124 in parallel. It records and prints color images at high speed.

  In the color image forming apparatus according to this embodiment, as described above, the four optical scanning devices 161, 162, 163, and 164 use the light beams based on the respective image data to respectively correspond the latent images of the respective colors to the photosensitive drums 121 and 122, respectively. , 123, and 124. Thereafter, a single full color image is formed by multiple transfer onto a recording material.

  As the external device 152, for example, a color image reading device including a CCD sensor may be used. In this case, the color image reading apparatus and the color image forming apparatus 160 constitute a color digital copying machine.

Example 3
Example 3 relates to molding an optical element using a mold for an optical element having a convex-concave (protrusion) nickel uneven structure on a nickel substrate.

  In Example 3, similarly to Example 1, by providing a plurality of concave pores having an antireflection function on the surface of an optical element having a finite curvature, a uniform antireflection characteristic is provided on the entire optical surface. It is expressed.

[Optical Element Manufacturing Method 3]
The optical element manufacturing method 3 according to the third embodiment relates to molding an optical element using a mold for an optical element having a cylindrical nickel uneven structure (protrusion) on a nickel substrate.

The optical element manufacturing method 3 will be described.
As in optical element manufacturing methods 1 and 2, first, a mold having a free curved surface for forming an fθ lens (optical element) is prepared, and a mold having a free curved surface covered with a nickel-silicon oxide mixed film by sputtering. Got. Here, the nickel-silicon oxide mixed film was formed by a magnetron sputtering method using an RF power source. Two targets were used, a nickel target having a diameter of 2 inches (50.8 mm) and a silicon oxide target. The film formation conditions are as follows: the input power of the nickel target is RF 30 W, the input power of the silicon oxide target is RF 70 W, the argon gas pressure is 0.11 Pa, the substrate temperature is 600 ° C., and the two targets are used simultaneously until the desired film thickness is obtained. Film formation was performed. FIG. 4A is a diagram schematically showing a cross-sectional image of a nickel-silicon oxide mixed film observed with an FE-SEM (field emission scanning electron microscope). In the nickel-silicon oxide mixed film 41 thus formed, a nickel (Ni) portion 42 is formed in a cylinder shape perpendicular to the nickel substrate 40. It was confirmed that a silicon oxide (SiO ₂ ) matrix region 43 surrounding the nickel (Ni) portion 42 was formed. Then, the entire mold is covered with a masking tape so that only the free curved surface is exposed. The surface other than the free curved surface is insulated and waterproofed by coating, immersed in an aqueous sodium hydroxide solution at room temperature to dissolve the silicon oxide (SiO ₂ ) surrounding the nickel (Ni) portion, and the nickel (Ni) protrusions are formed on the mold surface. A fθ mold having the above was obtained.

When the mold for the fθ lens thus obtained was observed with an FE-SEM (Field Emission Scanning Electron Microscope), it was found that a myriad of randomly arranged protrusions were standing perpendicular to the mold surface. . When the center coordinate position of the protrusion was obtained by image processing and the center distance D between the six adjacent pores was obtained, the center distance D between the adjacent pores was a period of about 300 nm. The mold manufactured by the above procedure is placed on the entrance surface side and the exit surface side of an injection molding machine (Sumitomo Heavy Industries, Ltd .: SS180), and a cycloolefin polymer (Nippon Zeon Corporation) is injection molded to produce an fθ lens. Got. At this time, the molten resin temperature was set to 270 ° C., and the holding pressure at the time of resin injection was set to 700 kg / cm ² .

  When the fθ lens thus obtained is observed with an FE-SEM (field emission scanning electron microscope), columnar pores randomly arranged over the entire curved surface are observed. It was confirmed that each columnar pore was formed in the normal direction of the surface.

  Further, the center position of the pores was obtained by image processing, and the average of the center distances D between the six adjacent columnar pores was obtained. The center distance D between the adjacent pores was about 300 nm. Yes, it was confirmed that the protrusions of the mold were transferred.

  Further, when the height of the columnar pores was measured with an atomic force microscope, the thickness of the pores was almost uniform toward the tip, the average depth was about 160 nm, and the volume ratio of the pores was about 46. %Met. Therefore, when the reflectance at the time of perpendicular incidence of P-polarized light with a wavelength of 780 nm was measured using a spectrophotometer, it was 0.6%.

[Optical Element Manufacturing Method 4]
The optical element manufacturing method 4 according to Example 3 relates to molding an optical element using a mold for an optical element having a conical uneven structure (projection) of nickel on a nickel substrate.

The optical element manufacturing method 4 will be described.
As in the optical element manufacturing method 3, first, a mold having a free curved surface for forming an fθ lens (optical element) is prepared, and a mold having a free curved surface covered with a nickel-silicon oxide mixed film by sputtering is obtained. It was. Here, similarly to the optical element manufacturing method 3, the nickel-silicon oxide mixed film was formed by a magnetron sputtering method using an RF power source. Two targets were used, a nickel target having a diameter of 2 inches (50.8 mm) and a silicon oxide target. As a film forming condition, a method of switching the input power to the two targets stepwise was adopted. First, as the first stage, the nickel target power was RF58W, the silicon oxide target power was RF0W, and the films were simultaneously formed at an argon gas pressure of 0.11 Pa and a substrate temperature of 600 ° C. for 5 minutes. Next, as a second stage, the power input to the nickel target was RF 46 W, the power input to the silicon oxide target was RF 28 W, and simultaneous film formation was performed at an argon gas pressure of 0.11 Pa and a substrate temperature of 600 ° C. for 5 minutes. . Subsequently, as a third stage, the input power to the nickel target is set to RF35W, and the input power to the silicon oxide target is set to RF55W. As a fourth stage, the input power to the nickel target is RF23W, and the input power to the silicon oxide target is RF83W. As a fifth stage, the input power to the nickel target is RF12W, and the input power to the silicon oxide target is RF110W. In each stage, simultaneous film formation was performed at an argon gas pressure of 0.11 Pa and a substrate temperature of 600 ° C. for 5 minutes. As described above, after the film formation was completed by switching the input power in five steps, the surface and the cross-sectional shape of the nickel-silicon oxide mixed film were observed with an FE-SEM (field emission scanning electron microscope). FIG. 4B is a diagram schematically showing a cross-sectional image of the nickel-silicon oxide mixed film observed with an FE-SEM (field emission scanning electron microscope). In the formed nickel-silicon oxide mixed film 41, a nickel (Ni) portion 42 is formed in a cylinder shape perpendicular to the nickel substrate 40, and a silicon oxide matrix region 43 surrounding the nickel (Ni) portion 42 is formed. It has been confirmed. Further, by changing the composition ratio of nickel-silicon oxide by switching input power, the diameter of the nickel (Ni) cylinder portion 42 can be continuously changed to form a film. As a result, it was confirmed that the diameter gradually decreased with increasing distance from the substrate, that is, a conical nickel (Ni) cylinder portion 42 was formed.

  Then, the entire mold is covered with a masking tape so that only the free curved surface is exposed. Other than the free-form surface, it is insulated and waterproofed by coating, immersed in an aqueous phosphoric acid solution at room temperature to dissolve silicon oxide surrounding the nickel-nickel (Ni) portion, and has nickel (Ni) protrusions on the mold surface for fθ I got a mold.

  The mold for the fθ lens thus obtained was observed with an FE-SEM (field emission scanning electron microscope). Innumerable protrusions of random arrangement stand vertically to the mold surface, and the center coordinate position of the protrusions is obtained by image processing, and the center distance D between the six adjacent pores is obtained. The center-to-center distance D between adjacent pores was a period of about 240 nm.

The mold manufactured by the above procedure is placed on the entrance surface side and the exit surface side of an injection molding machine (Sumitomo Heavy Industries, Ltd .: SS180), and a cycloolefin polymer (Nippon Zeon Corporation) is injection molded to produce an fθ lens. Got. At this time, the molten resin temperature was set to 270 ° C., and the holding pressure at the time of resin injection was set to 700 kg / cm ² .

  When the fθ lens thus obtained was observed with an FE-SEM (field emission scanning electron microscope), columnar pores randomly arranged over the entire curved surface were observed, and each columnar pore was a surface. It was confirmed that it was formed toward the normal direction.

  Further, the center position of the pores is obtained by image processing, and the average of the center distances D between the six adjacent columnar pores is obtained. The center distance D between the adjacent pores is about 240 nm. Yes, it was confirmed that the protrusions of the mold were transferred.

  Further, when the height of the columnar pores was measured with an atomic force microscope, the thickness of the pores was almost uniform toward the tip, the average depth was about 180 nm, and the volume ratio of the pores was about 40. %Met. Therefore, when the reflectance at the time of perpendicular incidence of P-polarized light with a wavelength of 780 nm was measured using a spectrophotometer, it was 0.6%.

Example 4
Example 4 relates to a method for manufacturing a mold having a convex lamellar uneven structure on a substrate. In this embodiment, a method for manufacturing a mold when an aluminum nickel mixed film is used will be described.

When the aluminum nickel mixed film is formed in a non-equilibrium state, two regions of a plurality of columnar members mainly composed of aluminum nickel (Al ₃ Ni) and a plurality of columnar members mainly composed of aluminum (Al) are in phase. Grows in a separate state. As shown in FIG. 13, a structure in which the aluminum nickel (Al ₃ Ni) 212 portion of the columnar member is divided by the aluminum (Al) columnar member 213 is formed.

At this time, in order to obtain the phase-separated aluminum-nickel mixed film as shown in FIG. 13, the ratio of nickel in the film needs to be 20 atomic% to 60 atomic%.
The ratio of the average value Dl in the major axis direction of the columnar member to the average value Ds in the minor axis direction (Dl / Ds) is 5 or more, and the average diameter in the minor axis direction is 5 nm or more and 300 nm or less. When forming a body, it is better to do as follows. It is preferable that the energy of aluminum and nickel is rapidly lost on the substrate and that surface diffusion occurs on a time scale at which phase separation of aluminum and nickel occurs.

  Furthermore, the diameter of the columnar members (in the minor axis direction) and the interval between the columnar members are 5 nm to 300 nm in diameter by changing the composition of the total thickness of the phase separation in the aluminum nickel mixed film, and the center interval distance between the columnar members is It changes within the range of 30 nm to 500 nm.

The film forming process of the aluminum nickel mixed film is not particularly limited as long as the film can be formed in a non-equilibrium state on the substrate. As a film forming method in a non-equilibrium state, a method performed in a gas phase or in a vacuum such as a sputtering method or an electron beam evaporation method is preferable, and a sputtering method is particularly preferable. In the sputtering method, simultaneous sputtering of an aluminum target and a nickel target can be applied. Alternatively, there are several methods such as sputtering using a mixed target formed by sintering an aluminum target and a nickel target, or sputtering using a nickel chip disposed on an aluminum target. The present invention is not particularly limited to these. In addition, the formation of the structure can be highly controlled by the distance between the sputtering target and the substrate in the sputtering method, the input power, the type of process gas, the pressure of the process gas, the substrate temperature, the bias applied to the substrate, and the like. Therefore, by optimizing the above film forming conditions, a structure in which the aluminum nickel (Al ₃ Ni) 212 portion of the columnar member of the present invention is divided by the aluminum (Al) columnar member 213 is formed.

In this embodiment, a nickel substrate (1.5 cm square) arranged on an aluminum target and a nickel substrate are selected. An uneven structure corresponding to an integral multiple of the period of the phase separation structure to be formed is formed in one direction on the nickel substrate. When an aluminum nickel mixed film is formed on this substrate, as shown in the schematic diagram of FIG. 15, the structure of the present invention, that is, aluminum nickel (Al ₃ Ni) and aluminum (Al) are formed along the concavo-convex structure. It becomes possible to arrange the phase separation structure. The concavo-convex structure is suitable for imparting anisotropy to the diffusion of aluminum and nickel forming the structure, but is not limited thereto. For example, the deposition of aluminum and nickel at the time of film formation can be performed by giving anisotropy to the direction of motion of the raw material itself incident on the substrate by performing oblique deposition with respect to the substrate.

  Further, the aluminum columnar member 213 is selectively dissolved by etching the structure schematically shown in FIG. Accordingly, it is possible to form a lamella-shaped concavo-convex structure having a convex portion (hereinafter referred to as a protrusion) 232 as shown in FIG.

That is, in the manufacturing method of a mold having a convex lamellar concavo-convex structure on a substrate, first, an aluminum nickel mixed film is formed in a non-equilibrium state on a nickel substrate having anisotropy. Secondly, aluminum of a columnar member is obtained from a mixed film having a plurality of columnar members mainly composed of aluminum nickel (Al ₃ Ni) obtained by film formation and a plurality of columnar members mainly composed of aluminum (Al). The (Al) portion is selectively removed by etching with phosphoric acid or aqueous ammonia. A mold made of nickel (Ni) or aluminum nickel (Al ₃ Ni) can be manufactured.

Further, regarding the aspect ratio of the concavo-convex structure and the volume ratio between the substrate and the atmosphere, the depth of the concavo-convex structure (projection) of lamellar aluminum nickel (Al ₃ Ni) of the columnar member shown in FIG. Is preferably 100 nm or more. Furthermore, it is preferable that the cross-sectional area ratio of the concavo-convex structure of the lamellar aluminum nickel (Al ₃ Ni) with respect to the nickel substrate is in the range of 40% to 80%. Here, the cross-sectional area ratio of the lamella-shaped concavo-convex structure can be controlled by a method of changing the composition ratio of aluminum and nickel in the aluminum nickel mixed film. Further, by controlling the sputtering time in consideration of the film formation rate of aluminum and nickel, the desired depth of the concavo-convex structure can be obtained.

  In addition, the uneven structure according to the present invention is not limited to the one having the lamellar shape shown in FIG. 15A, and includes any shape that can be realized by a combination of film forming conditions and composition ratios.

Furthermore, in the mold having a lamellar uneven structure on the substrate of the present invention, an adhesive layer 231 is provided between the nickel substrate and the aluminum nickel (Al ₃ Ni) or nickel (Ni) columnar member as shown in FIG. The structure of (B) may be sufficient. As the adhesive layer, titanium (Ti), nickel (Ni), and alloys containing them are preferable.

Example 5
The fifth embodiment relates to a method of manufacturing a mold having a convex lamellar uneven structure as in the third embodiment. In this example, a method of manufacturing a mold when using a mixed film of gold (Au) and nickel (Ni), which is mentioned as a material that does not form a compound with nickel, will be described. When gold and nickel are sputtered simultaneously in a non-equilibrium state, they are separated into two regions of a plurality of columnar members mainly composed of nickel (Ni) and a plurality of columnar members mainly composed of gold (Au). At this time, the shape of the columnar member mainly composed of nickel (Ni) (or gold (Au)) is formed by crystallized nickel and gold crystal grain boundaries. Contains.

  As in Example 3, the diameter (short axis direction) of the columnar members and the interval between the columnar members are 10 nm or more in diameter (short axis direction) by changing the composition ratio of nickel and gold in the gold-nickel mixed film. Can be 200 nm or less. The interval can be changed in the range of 30 nm to 500 nm. As a method of changing the composition ratio of nickel and gold in the gold-nickel mixed film, there is a method of laminating the gold-nickel mixed film while gradually changing the film forming rate. Or the method of laminating | stacking a gold-nickel mixed film using the target from which at least 2 or more types of composition ratios differ is mentioned. In the case of using a sputtering method, the film formation rate can be changed by controlling film formation conditions such as input power, sputtering pressure, substrate bias, and substrate temperature.

  Further, a gold-nickel mixed film is formed on a substrate having anisotropy by the same method as in Example 3. Then, the gold (Au) portion of the columnar member is obtained from a mixed film having a plurality of columnar members mainly composed of nickel (Ni) obtained by film formation and a plurality of columnar members mainly composed of gold (Au). Dissolve selectively with gold etchant. Thus, a mold made of nickel (Ni) can be produced.

Example 6
Example 6 relates to molding an optical element using a mold for an optical element having a concavo-convex structure of a convex (projection) lamellar aluminum nickel on a nickel substrate.

  FIG. 16A is a schematic view schematically showing a cross section of a plurality of grooves obtained by the mold of the embodiment of the present invention. Reference numeral 242 in the figure denotes a fine groove (concave portion), which has an antireflection function and is randomly provided on the surface (base shape is concave or convex) of the optical element 241 having a finite curvature. Yes. The fine groove (concave portion) is formed of a periodic structure in which two portions of a convex columnar structure and a concave columnar structure are arranged in a one-dimensional direction, and has a lamellar shape having a rectangular groove cross section. It is made. Each of the plurality of grooves 242 has substantially the same concave shape, and is formed independently in the normal direction of the surface of the optical element 241.

  Here, the antireflection function refers to a function of reducing the reflectance of the surface provided with the groove as compared with the reflectance of the mirror surface, and preferably the reflectance is 1% or less. The plurality of grooves 242 are formed by molding on the surface of the optical element having a finite curvature.

  In the present embodiment, among the plurality of grooves 242, the center interval distance D (corresponding to the length of one period of a rectangular lamellar shape in the short axis direction) of adjacent grooves 242 is set, and the wavelength used is λ. And when

Is set to satisfy the following conditions.
Here, the conditional expression (1) defines the upper limit of the center-to-center distance D in the minor axis direction of the adjacent grooves 242. That is, exceeding the upper limit of the conditional expression (1) is not preferable because it becomes difficult to develop an excellent antireflection characteristic on the entire optical surface. The lower limit is not functionally limited, and may be as small as possible as long as the volume ratio between the groove and the atmosphere described later is appropriate.

  The center-to-center distance D in the minor axis direction of adjacent grooves 242 is the groove center-to-center distance in the minor axis direction in a groove having a lamellar shape with a rectangular cross section arranged in a certain direction. Call it. That is, for all the grooves in the measurement region, the average of the center-to-center distances in the minor axis direction with respect to the adjacent grooves is obtained, and the average value is set as the center-to-center distance of the grooves in the array.

  In this embodiment, a plurality of grooves having substantially the same concave shape as described above are formed independently on the surface of the optical element having a finite curvature in the normal direction of the surface. By exhibiting an antireflection function in a direction perpendicular to the direction in which the plurality of grooves are arranged, uniform antireflection characteristics are obtained over the entire optical surface.

  In order to exhibit the antireflection function in this embodiment, it is particularly preferable that the interval between adjacent grooves is equal to or less than ½ of the design wavelength λ of an optical element that is said to generate no 0th-order diffracted light. .

Therefore, in this embodiment, the antireflection function is manifested by setting the center distance D between adjacent grooves so as to satisfy the conditional expression (1).
Here, the design wavelength refers to the wavelength of light that is transmitted through or reflected by the optical element, and refers to a wavelength that is intended to suppress the amount of reflected light. For example, when it is desired to transmit visible light through an optical element and suppress the amount of reflected light having a wavelength of 600 nm or less, the design wavelength is regarded as 600 nm, and the interval between adjacent pores is preferably 300 nm or less. Alternatively, the laser beam printer exemplified in the above-mentioned problem uses laser light of 780 nm or less, and the interval between adjacent grooves is preferably 390 nm or less.

  In this embodiment, an optical element is described using a mold for an optical element having a concavo-convex structure of convex-shaped (projection) lamellar aluminum nickel. In this regard, it is also possible to mold the optical element using a mold for an optical element having a concave-convex (groove) lamellar aluminum-nickel uneven structure.

Next, the manufacturing method of the optical element of this invention is demonstrated.
In addition, the manufacturing method of this invention is not limited to the manufacturing method shown below. In the present invention, the antireflection of a 780 nm P-polarized laser is targeted. However, the antireflection characteristic of the optical element obtained by the present invention is not limited to a single wavelength laser, and visible light, ultraviolet light, infrared light. It is applicable to.

  In the present invention, a mold for an optical element having a concavo-convex structure of nickel or a nickel alloy having a lamellar projection formed from a structure obtained by a film forming process of nickel and a material that phase separates from nickel is manufactured. Process is used. Furthermore, an optical element is formed using an element forming step of forming a lamellar groove by transferring the protrusion using the mold.

  Alternatively, in the present invention, a mold for an optical element having a concavo-convex structure of nickel or a nickel alloy having a lamellar groove formed from a structure obtained by a film forming process of nickel and a material that phase separates from nickel. The manufacturing process is used. Furthermore, an optical element is formed using an element forming step of forming a lamellar protrusion by transferring the groove using the mold.

Here, the period and size (width and height) of the lamella-shaped protrusion (or groove) can be controlled by appropriately selecting conditions.
In other words, by appropriately selecting the film forming conditions by the sputtering method, it is possible to form desired protrusions (or grooves) all over the mold surface, and to form SWS in a short time and at low cost. It is.

  In addition, as a means for transferring the projection (or groove) formed on the mold, any molding means such as injection, replica, press, casting, etc. may be used, but injection and press molding capable of efficiently transferring SWS together with the substrate. Is particularly preferred. Further, when releasing from the mold, the direction of the protrusion (or groove) and the releasing direction are not necessarily parallel. However, while the groove (or protrusion) formed by transferring the protrusion (or groove) can tolerate a certain degree of deformation, it can be easily released, for example, by releasing before the groove is completely solidified. it can.

  In particular, in the mold having a lamella-shaped protrusion (or groove) of the present invention, the ratio (Dl / Ds) of the diameter Dl in the major axis direction to the diameter Ds in the minor axis direction is 5 or more, and the shape of the protrusion Has a length in a direction perpendicular to the direction in which the mold is released. Therefore, it has better durability than molds having columnar or conical protrusions (or pores) and has excellent releasability, and the mold can be easily released without destroying the SWS. it can.

[Method for Manufacturing Optical Element]
The method for manufacturing an optical element according to Example 6 relates to molding an optical element by using a mold for an optical element having a concavo-convex structure (projections) of lamellar aluminum nickel on a nickel substrate.

A method for manufacturing the optical element will be described.
First, a mold having a free curved surface for forming an fθ lens (optical element) was prepared, and a primer layer and an aluminum nickel layer were uniformly formed on the free curved surface in this order by sputtering and covered with an aluminum nickel mixed film. A mold having a curved surface was obtained. Here, a concavo-convex structure was formed in a certain direction with a period of 200 nm with respect to a mold for forming an aluminum nickel layer in advance. This was formed by a tape varnish made of a polishing tape soaked with diamond slurry or the like, and an aluminum nickel mixed film was formed on this mold by a magnetron sputtering method using an RF power source. The target used was a 4 inch (101.6 mm) diameter aluminum target with a nickel chip (1.5 cm square) arranged. Film formation was carried out until the desired film thickness was obtained with an input power of RF 120 W, an argon gas pressure of 0.11 Pa, and a substrate temperature of 400 ° C.

FIG. 13 is a diagram schematically showing a cross-sectional image of an aluminum nickel mixed film observed with an FE-SEM (field emission scanning electron microscope). In the formed aluminum nickel mixed film 211, a columnar structure is formed in which the aluminum nickel (Al ₃ Ni) portion 212 is perpendicular to the nickel substrate 210 in the volume direction of the film. It was confirmed that an aluminum columnar structure surrounding the aluminum nickel (Al ₃ Ni) portion 212 was formed. Then, the entire mold is covered with a masking tape so that only the free curved surface is exposed, and the parts other than the free curved surface are insulated and waterproofed by covering. Then, the aluminum surrounding the aluminum nickel (Al ₃ Ni) portion is dissolved by dipping in an aqueous phosphoric acid solution at room temperature. Thus, an fθ mold having aluminum nickel (Al ₃ Ni) protrusions on the mold surface was obtained.

When the mold for the fθ lens thus obtained was observed with an FE-SEM (field emission scanning electron microscope), the lamella-shaped protrusions arranged along the textured uneven structure were perpendicular to the mold surface. I can see you standing. The center position in the minor axis direction of the projection was obtained by image processing, and the center distance D between adjacent projections in the minor axis direction of the projection was obtained. The distance D between the centers of adjacent protrusions in the minor axis direction was a period of about 200 nm. The molds manufactured by the above procedure are arranged on the entrance surface side and the exit surface side of an injection molding machine (Sumitomo Heavy Industries, Ltd .: SS180). A cycloolefin polymer (manufactured by Zeon Corporation) was injection molded to obtain an fθ lens. At this time, the molten resin temperature was set to 270 ° C., and the holding pressure during resin injection was set to 700 kg / cm ² .

Note that if the substrate gets in the way when removing the resin from the mold, the substrate can be removed in advance, and then the resin can be filled and released from both sides of the pores. The same applies to the above-described embodiments.
When the fθ lens thus obtained was observed with an FE-SEM (Field Emission Scanning Electron Microscope), lamella-shaped cross-sectionally rectangular grooves arranged randomly throughout the curved surface were observed, and each cross-sectional rectangular shape was observed. These grooves were confirmed to be formed toward the normal direction of the surface.

  Further, the center position of the groove having a rectangular cross section is obtained by image processing, and the average of the center distance D (the minor axis direction of the groove) between adjacent grooves is obtained. The center-to-center distance D was approximately 200 nm, and it was confirmed that the mold protrusions were transferred.

  Further, when the shape of the lamellar groove was measured with an atomic force microscope, the groove width was almost uniform toward the tip, the average depth was about 160 nm, and the groove volume ratio was about 60%. . Therefore, when the reflectance at the time of perpendicular incidence of P-polarized light with a wavelength of 780 nm was measured using a spectrophotometer, it was 0.6%.

  The optical element molded using the optical element mold of the present invention has a function of suppressing the amount of interface reflection at the light incident / exit surface. For example, it can be suitably used for imaging equipment such as cameras and video cameras, and projection equipment such as liquid crystal projectors and optical scanning devices for electrophotographic equipment.

It is the schematic diagram which represented typically the mixed film of the material which phase-separates with nickel and nickel explaining the manufacturing method of the metal mold | die of this invention. It is the schematic diagram which represented typically the aluminum nickel mixed film explaining the manufacturing method of the metal mold | die of this invention. It is the schematic diagram which represented typically the aluminum nickel mixed film explaining the manufacturing method of the metal mold | die of this invention. It is the schematic diagram which represented typically the cross section of the aluminum nickel mixed film explaining the manufacturing method of the metal mold | die for optical elements of this invention. It is the schematic diagram which represented typically the cross section of the metal mold | die for optical elements of this invention. It is the schematic diagram which represented typically the cross section of the metal mold | die for optical elements of this invention. It is the schematic diagram which represented typically the cross section of the optical element of the Example of this invention. It is the schematic diagram which represented typically the cross section of the pore or protrusion which concerns on the Example of this invention. It is the schematic diagram which represented typically the arrangement | sequence of the pore or protrusion which concerns on the Example of this invention. It is sectional drawing of the principal part of the optical scanning device carrying the optical element of this invention. 1 is a cross-sectional view of a main part of an image forming apparatus of the present invention. 1 is a cross-sectional view of a main part of a color image forming apparatus of the present invention. It is the schematic diagram which represented typically the aluminum nickel mixed film explaining the manufacturing method of the metal mold | die of this invention. It is the schematic diagram which represented typically the aluminum nickel mixed film explaining the manufacturing method of the metal mold | die of this invention. It is the schematic diagram which represented the cross section of the metal mold | die of this invention typically. It is the schematic diagram which represented typically the cross section of the groove | channel which concerns on the Example of this invention.

Explanation of symbols

1 Light source means (semiconductor laser)
DESCRIPTION OF SYMBOLS 2 Collimator lens 3 Aperture stop 4 Cylindrical lens 5 Optical deflector 5a Deflection surface 6 Imaging optical means 6a, 6b f (theta) lens 6a1, 6b1 Incident surface 6a2, 6b2 Output surface 7 Scanned surface 10, 20, 30, 40, 50, 60, 230 Substrate 11, 41 Mixed film 12, 42 Cylinder 13, 32, 43 Matrix 21, 51, 61, 232 Convex part 22, 52, 62, 233 Concave part 31 Pore 63, 231 Adhesive layer 71, 81 Optical element 72, 82, 92 Fine hole 100 Optical scanning device 101 Photosensitive drum 102 Charging roller 103 Light beam 104 Image forming device 107 Developing device 108 Transfer roller 109 Paper cassette 110 Paper feed roller 111 Printer controller 112 Transfer material (paper)
113 Fixing roller 114 Pressure roller 115 Motor 116 Paper discharge roller 117 External device 121, 122, 123, 124 Image carrier (photosensitive drum)
131, 132, 133, 134 Developer 141, 142, 143, 144 Light beam 151 Paper transport path 152 External device 153 Printer controller 160 Color image forming device 161, 162, 163, 164 Optical scanning device 210 Substrate 211 Mixed film 212 First One columnar member (aluminum nickel)
213 Second columnar member (aluminum)
241 Optical element 242 Groove

Claims (18)

  A method of manufacturing a mold having a concavo-convex structure on a substrate, comprising: simultaneously forming a first material and a second material phase-separated from the first material on the substrate; and A plurality of cylinders comprising the obtained first material as a component, and a matrix region comprising the second material surrounding the plurality of cylinders as a component, and at least one of the first and second materials And a step of producing a mold having an uneven structure made of the first material by removing the matrix portion from the mixed film containing nickel in one side.   A method of manufacturing a mold having a concavo-convex structure on a substrate, comprising: simultaneously forming a first material and a second material phase-separated from the first material on the substrate; and A matrix region composed of the first material obtained as a component, and a plurality of cylinders composed of the second material surrounded by the matrix region, wherein at least one of the first and second materials And a step of producing a mold having an uneven structure made of the first material by removing the cylinder portion from a mixed film containing nickel in either one of them.   A plurality of concavo-convex structures are arranged on the substrate and are composed of the first material, the period of the concavo-convex structure is in the range of 30 nm to 500 nm, and the depth of the concavo-convex structure is 100 nm or more. The method for manufacturing a mold according to claim 1.   A step of simultaneously forming a material for phase separation of nickel and nickel on a nickel substrate; a plurality of cylinders containing nickel obtained by the film formation step; and surrounding the plurality of cylinders; 2. The mold according to claim 1, further comprising a step of etching and removing the matrix portion from a mixed film having a matrix region containing a material to be separated as a component to produce a mold made of nickel or a nickel alloy. Production method.   A step of simultaneously forming a material that phase-separates nickel and nickel on a nickel substrate, a matrix region containing nickel obtained by the film-forming step as a component, and surrounded by the matrix region and phase-separated from nickel And a step of producing a mold made of nickel or a nickel alloy by etching away the cylinder portion from a mixed film having a plurality of cylinders containing a material to be processed as a component. Production method.   5. The mold manufacturing method according to claim 4, wherein the mold made of nickel or a nickel alloy controls the shape of the cylinder by changing the composition ratio of the material that phase-separates nickel and nickel in the mixed film. .   5. The material phase-separated from nickel contains at least one of aluminum, magnesium, titanium, yttrium and zirconium having a eutectic equilibrium diagram with nickel. Mold manufacturing method.   The method for producing a mold according to claim 4, wherein the material phase-separated from nickel contains at least one of silver and gold that do not form a compound with nickel.   The mold manufacturing method according to claim 4, wherein the mold made of nickel or a nickel alloy is formed by a plurality of convex-shaped cylindrical or conical uneven structures.   6. The mold manufacturing method according to claim 5, wherein the mold made of nickel or a nickel alloy is formed by a plurality of concave columnar or conical concavo-convex structures.   An optical element mold manufactured by the method for manufacturing an optical element mold according to claim 1. A mold manufacturing method of having an uneven structure on a substrate, a step of simultaneously forming a second columnar member that columnar members and phase separation of the first columnar member and said first on the substrate, the formed A columnar member composed of one of the phases is dissolved from the mixed film having a two-phase separation structure composed of the first and second columnar members obtained by the membrane process, and is composed of the other phase. The manufacturing method of the type | mold characterized by including the process of producing the metal mold | die consisting of the columnar member made. The concavo-convex structure is composed of any one phase of a mixed film having a two-phase separation structure that is arranged in plurality on the substrate and composed of the first and second columnar members, and either one of the above. The ratio of the average diameter Dl in the major axis direction to the average diameter Ds in the minor axis direction in the phase is 5 or more, the period of the concavo-convex structure is in the range of 30 nm to 500 nm, and the depth of the concavo-convex structure The method for producing a mold according to claim 12 , wherein is 100 nm or more. 13. The mold manufacturing method according to claim 12 , wherein an average diameter in a minor axis direction of the first columnar member or the second columnar member is 5 nm or more and 300 nm or less. In mixed film having the first a two-phase separation structure composed of a second columnar member, of the type according to claim 12, characterized in that the separation structure with a single direction is formed Production method. Constructed in one phase, including a step of simultaneously depositing nickel and a phase-separating material on a nickel substrate, and a member that phase-separates nickel from a mixed film having a two-phase separation structure obtained by the film-forming step The method of manufacturing a mold according to claim 12 , further comprising: a step of etching and removing a columnar member to be manufactured to produce a mold made of nickel or a nickel alloy. The nickel or mold made of nickel alloy, according to claim 16, characterized by controlling the shape of the columnar member by varying the composition ratio of the material to phase separate the nickel and nickel in the mixed layer Mold manufacturing method. The mold manufacturing method according to claim 16 , wherein the mold made of nickel or a nickel alloy is formed by a plurality of lamella-shaped uneven structures having a convex shape or a concave shape.

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